Thoughts on Cat 623

[JustinG]

There's a local guy not far from me that has a Cat 623 for sale. Overall the machine is decent, early 80's model and tires in good shape. Bowl and flight bars in fair shape. Only problem is the engine has a knock. Apparently it started knocking one morning and so they took to their shop and has set for nearly a year. The knock sounds like it might be the bottom end. Asking price is $12,000. I dont mind having to do repairs and of course stuff like this is a gamble.

Wondering what others think about the price. These scrapers don't really bring much around here, not many 623's in my area. Of course, without knowing exactly what the engine issue is, I'm thinking new engine for worst case situation.

 

[02Dmax]

Depends on what you need to do with it I'd say. I've seen good running ones sell for the same price.

I assume it has the 3306?

 

[JustinG]

I have a pond project to do and some finish work that it could do also. I believe it has a 3406 in it.

 

[mowingman]

What model 623. Model B, E, or newer?

 

[JustinG]

B model 623

 

[Shimmy1]

Unless the knock is a wrist pin, it's going to need a crank. The real question is it going to need a block because a main bearing has spun.

 

[JustinG]

That's what I'm worried about. Spun mains is what worries me the most.

 

[Shimmy1]

If you can pull the pan without dragging the axle out, maybe a look is in order to see what your up against. If you don't buy it, all it'll cost you is some time and a pan gasket.

 

[Buckethead]

I believe it has a 3406 in it.

I think a 623B and E, and maybe F would be a 3306, newer than that is whatever the number Cat changed the 3306 to.

 

[Mark250]

Hi all, 623B run the 3406 engine
have you checked the filter for debris or the scavenge screens these machines run a wet clutch in the flywheel and have been known to cause knocking issues when the diaghram springs break

Regards Mark

 

[JustinG]

I was thinking I would remove the oil filter and cut the filter element apart. Where are the scavenge screens located on these machines?

 

[mowingman]

Lot of good suggestions here. In my experience, the B series is probably the best of all the 623's. Of course, all paddle scrappers are money pits over time. But, If I were still buying scrappers, I would be looking for used 623B's. There are hundreds of those still in use here in Texas alone. Very popular machines. Price sounds good, IF, you are not afraid of the possible repair issues. Get it running, and you can easily sell it and get your total investment back in the future.

 

[Buckethead]

Hi all, 623B run the 3406 engine

Come to think of it, you're right. I do think they had 3406. It's been a while, got my engines mixed up.

 

[Mark250]

just a thought , the transmission drive shaft runs from the safety clutch through the hydraulic retarder( if fitted) to the rear of the transmission transfer gears if the engine mounts are shot it upsets this alignment and causes all sorts or noise and vibration problems
to isolate remove the three bolts at rear of transmission, remove the cover plate ,remove the internal circlip and there is a threaded hole on the drive shaft that can be used the pull the axle back there is no need to remove it completely and run machine to check for your noise
this is assuming that the engine oil filters are not showing metal
Regards
mark

 

[JustinG]

just a thought , the transmission drive shaft runs from the safety clutch through the hydraulic retarder( if fitted) to the rear of the transmission transfer gears if the engine mounts are shot it upsets this alignment and causes all sorts or noise and vibration problems
to isolate remove the three bolts at rear of transmission, remove the cover plate ,remove the internal circlip and there is a threaded hole on the drive shaft that can be used the pull the axle back there is no need to remove it completely and run machine to check for your noise
this is assuming that the engine oil filters are not showing metal
Regards
mark

Very good info, thanks!

 

[RayF]

Another thing worth checking would be the cushion hitch. They can be a big dollar item if let go. I've made more than a few dollars line boring cushion hitch's.

 

[JustinG]

Definitely a engine problem, metal in oil filter pleats. Engine is not locked up, hopefully it's a rod rather than a main bearing.

 

[ShaneK]

Definitely a engine problem, metal in oil filter pleats. Engine is not locked up, hopefully it's a rod rather than a main bearing.

This is why I much prefer pull-pan scrapers. No engine issues to deal with, and better resale value!

 

[lantraxco]

This is why I much prefer pull-pan scrapers. No engine issues to deal with, and better resale value!

So what makes them go then, 20 mule team? LOL! :tong

 

[Heavey Metal]

They where bad about breaking the crank

Knock but still pull

It knaws the front main bad in the rebuild book the core is still reusable if it hasn't knawed clear to the oil hole.

Take a prybar to the dampner to diagnose.